The discovery of a novel sulfatase of unusual specificity and the synthesis of isomeric glucosamine sulfates of known structure have led to the discovery that heparin contains a unique 3-0 sulfated glucosamine residue which is essential for its role as an anticoagulant. The enzyme has been partially purified from human urine. Many polyanions, including heparin, induce allosteric changes in hemoglobin which markedly affect its solubility. In a study of allosteric effects of polyanions of controlled size, highly sulfated trehalose and stachyose have been prepared. These compounds bind with high affinity to hemoglobin-S and strongly decrease its affinity for oxygen. Studies of the effects of these and other highly sulfated sugars on the solubility of hemoglobin-S are being carried out.